Series/Parallel Cap question

I've just started an electronics course and I've already found this site invaluable in my understanding of electronics in general. I've been assigned a series of questions to complete as part of my year and I'm just wondering if someone could give me a little help.

These are the diagrams I have been given. I'm asked to "Write the parametric equations for the above network and calculate the values of A, B, C and D parameters, at a frequency of 1kHz, "

I'm trying to add up the impedances of each component. Obviously the resistors are no problem but I'm having trouble with the cap. I'm just having trouble trying to see if it's in parallel or series with the other resistors. I'm thinking series but I'd just like to be sure before I do the calculations. I'll probably have one or two more q's , hence the big thread